iwlwifi: use a macro for default probe length

Instead of assigning the default max probe length to 200 in the main
code, create a macro for consistency and clarity.

Signed-off-by: Luciano Coelho <luciano.coelho@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/drivers/net/wireless/iwlwifi/iwl-drv.c b/drivers/net/wireless/iwlwifi/iwl-drv.c
index d0162d4..e88397b 100644
--- a/drivers/net/wireless/iwlwifi/iwl-drv.c
+++ b/drivers/net/wireless/iwlwifi/iwl-drv.c
@@ -843,7 +843,7 @@
 	int i;
 	bool load_module = false;
 
-	fw->ucode_capa.max_probe_length = 200;
+	fw->ucode_capa.max_probe_length = IWL_DEFAULT_MAX_PROBE_LENGTH;
 	fw->ucode_capa.standard_phy_calibration_size =
 			IWL_DEFAULT_STANDARD_PHY_CALIBRATE_TBL_SIZE;